“I’m back!” she says about the hair, pushing a red lock out of her eyes. “Back in business!”

Stone is actually a natural blond — and briefly returned to that color to play Gwen Stacy in “The Amazing Spider-Man,” due next year. But for most of her movies — such as last year’s surprise hit “Easy A” and the just opened romantic comedy “Crazy, Stupid, Love” — she’s gone scarlet.

The color suits her.

“When I dyed my hair red again, my best friend since I was 11 walked into my apartment and said, ‘You know, you look funnier as a redhead — you looked like such a bitch when you were blonde,’ ” Stone says, before breaking into a husky laugh.

“‘Well, thank you very much, Max!’ So apparently I was a bitchy kid all those years. Good to know!”

Stone is only 22, but seems to be Having a Moment, as the celebrity fame-charters say. Earlier this month she had a raunchy cameo in the Justin Timberlake comedy “Friends With Benefits.” Then came this weekend’s “Crazy, Stupid, Love” where — in her first really adult role — she got a sweetly comic love scene with Ryan Gosling.

And next month she gets a big dramatic part in “The Help,” a story about the civil rights era as seen through the eyes of a privileged young white woman who begins to question that privilege.

“When I read the novel, I saw Joan Cusack at 20, and thought, well, who’s Joan Cusack at 20,” says “The Help” director Tate Taylor. “Then I met Emma. And I thought, she is so damn smart, and so funny, and self-deprecating without being pitiful. … She was just perfect.”

It all adds up to a lot of exposure — but it’s unlikely anyone is going to tire of Stone soon.

Her slightly cracked alto, freckles and bright red hair — for however long she keeps it this time — make her a welcome change from Hollywood’s identical, affectless 20-somethings. And she has the acting skills, too, including a casually sarcastic delivery that makes even the most carefully scripted joke sound ad-libbed.

“I love improv,” she declares. “ ‘Crazy, Stupid, Love,’ the script was really great, but the directors were open to letting you try different things. And that felt like a muscle I hadn’t exercised in a really long time.”

Early anxiety

Stone grew up in Scottsdale, Ariz., where her father was a contractor and her mother took her to acting classes. A lot of acting classes, after Stone became “this really anxious kid” in grade school.

“Do you know Jesse Eisenberg and I both had our first panic attack at 8?” she says. “We found that out on ‘Zombieland’ and bonded immediately. But yeah, I had separation anxiety, I worried my house was going to burn down, I was wringing my hands all the time, and so my parents took me to a therapist. And so I was figuring things out and something happened where I just thought, okay, all right, I want to act.”

Stone’s improv training began when her mother took her to an audition for a spot in a local youth theater’s acting program. Instead of putting her in class, the theater put her in their new play. Then, they invited her to join their improv troupe.

“And that changed my anxiety forever,” Stone says. “Forever. You know how sports teach kids teamwork, and how to be strong and brave and confident? Improv was my sport. I learned how to not waffle and how to hold a conversation, how to take risks and actually be excited to fail. It taught me so much, and helped me overcome so much. And I realized, okay, this is my job.”

“She’s just like me where she takes her job seriously but she likes to be involved in things which are funny,” says Eisenberg. “Emma’s naturally very, very funny. But when she does come up with something funny, it’s never at the expense of the character’s authenticity.”

After a couple of years of home schooling — and one semester of all-girls prep — Stone convinced her parents to let her drop out and move to Hollywood. She was 15. Her mother moved out with her and Stone began the trudge in and out of auditions,

It was a long series of near-misses. She went through nearly endless callbacks for “Heroes” — and then saw the part go to Hayden Panettiere. She landed the “Laurie” role on something called “The New Partridge Family” — but then the pilot was never picked up.

“There’s an old Garth Brooks song — my mom always used to drive around listening to country songs — and it’s like, ‘Some of God’s greatest gifts are unanswered prayers,’ ” Stone says. “And there are so many prayers I’m grateful went unanswered! Things are crazy enough now at 22, but if all this had happened at 15, I couldn’t even imagine it. … Really, sometimes it’s the things that don’t happen that make you who you are.”

‘Love it or hate it’

It was one of the things that happened, though — getting cast, at 18, as the hostess of the infamous party in “Superbad” — that made Stone’s career. The next year she got two movies, “The Rocker” and “The House Bunny.” The following year brought three, including the surprise hit “Zombieland.” None had been written for her, yet each of them seemed to be.

“I’m not one of those shoppers where I go to a store and I’m like, trying it on, I’m not sure, ‘Oh, can you put this on hold?’ ” she says. “No. It’s either love it, or hate it. And it’s the same way with scripts. I usually know within the first 10 pages. If I don’t latch into it by then, then it’s not going to happen.”

One of the scripts it happened with, immediately, was for “Easy A,” the high-school comedy about the snarky virgin who decides to invent a bad reputation — and soon regrets it.

“I think your characters kind of pick you,” Stone says. “And reading Olive in ‘Easy A,’ that was like, I just wanted to crawl inside the script and hold onto that character and say ‘Mine, mine, mine.’ I just thought, man, don’t (mess) this up, you have to audition really well and get this. I just loved her, and wanted to protect her and really be a part of that movie.”

“Easy A” was Stone’s first real starring role — an important step forward for the actress. It’s been followed rapidly by other milestones, including her first real adult part (in “Crazy, Stupid, Love”) and her first lead in a big drama (in “The Help”).

Add in next year’s hopeful blockbuster, “The Amazing Spider-Man,” and you realize she’s packed a decade’s worth of turning points into a very short period. It’s enough to make anyone dizzy — which is why Stone keeps her eyes half-closed.

“My manager’s been with me since I’m 16 and I trust him like crazy,” she says. “And he and the people around me — they definitely know what not to tell me. That’s always been my thing, just share what’s necessary. I just can’t possibly think of how a role changes my image, or what path it puts my career on. Please, no, I’d go crazy.”

Emma Stone has a ton of movies coming out this summer (including this film which she starts in called "The Help" which will be out in August)

Acting earthbound

Not that she doesn’t stay fully aware of — and remain eager for — the challenges.

“The Help” for example, is her first period film — even if what’s “period” for her is just the well-remembered past for older adults. And she loved finding Skeeter, the dutiful Southern daughter, through wardrobe.

“I’ve never played someone where I felt it was beneficial to build from the outside in,” she explains. “For me, the internal stuff always came first. But I understood Skeeter most when I got in her clothes, and that hair and that girdle — it was as if the physical constrictions mirrored the constraints she was living under.”

Yet what would seem to be a really daunting step — jumping into the middle of a special-effects extravaganza like the new “Spider-Man” — didn’t worry her at all.

“It wasn’t wildly different from other things I’ve done,” Stone says. “It’s a very big environment, but my scenes with Andrew (Garfield) really tell a much smaller story about falling in love and being in a relationship for the first time. So my part of it is very earthbound.”

Staying earthbound in her personal life is important to Stone, and something she’s still negotiating. She has an apartment in the city and reportedly has had a few romances with co-stars. Personally, though, she still feels “kind of in this limbo stage.”

She’s currently reading Lauren Bacall’s book “By Myself.” While Stone “loves, loves, loves her” (she even trots out an impression in “Crazy, Stupid, Love” — it’s more Elizabeth Ashley, really, but no matter) the idea of being where Bacall was at her age — married and settled — seems both attractive and very far away.

“I so admire people like Woody (Harrelson) or Steve (Carell) who have found a way to have a real life and then go do a movie and then come home again,” she says. “I mean, I have a life, but I haven’t built my own actual family yet. I feel like I’m kind of all over the place. Maybe my biological clock just started ticking. Does it start now, at 22?”

“I don’t know,” she says after a moment, “but it’s hard, traveling and being away so much. You go into this microcosm of people and you get really close and then you leave and you never really see them again. And then you go somewhere else and do it all over again. It’s like one summer camp after another, without ever going home in between.”

So far, though, Stone has managed to always steer her way back to safety. She’s like the anti-Lindsay. There are no tabloid pictures of her falling out of a bar, or TMZ posts of a 3 a.m. mugshot, or even just stories of her turning into a jaded baby diva, trailed by enablers.

“I have the sheer luck of having parents who would never allow me to lose my mind like that,” she says. “I mean, they just would not let that happen. And I need that, knowing that they’re always going to be there for me. I’d be a mess without that. I need to have people to cry to. Because I don’t want to get calloused. I don’t want to grow a thick skin. You know, you see these actors sometimes, who’ve been famous for a long time, and they’ve grown like this rhino skin, emotionally? And it makes sense, it’s a defense mechanism. But then they can’t relate to people in the same way anymore, and you can see it onscreen. They can’t emote like they used to.